Nprach formats for nb-iot transmission in TDD mode

Abstract

Random Access (RA) formats are defined for NB-IoT operation in TDD mode. The formats are defined to allow use of the legacy LTE sub-frame configurations for TDD. The formats specify a predetermined, even number P of symbol groups composing a RA preamble, wherein each symbol group comprises a Cyclic Prefix (CP) and a number X of symbols. The P symbol groups are divided into symbol group sets fitting into 1, or 2, or 3 contiguous uplink sub-frames, each comprising at least two symbol groups transmitted back-to-back (i.e., contiguously in time), and at least two symbol group sets are transmittednon-contiguously in time across a number of uplink sub-frames over which the RA preamble is transmitted. The number of symbol groups in a set can be two or three, and the number of symbol groups is four or six, respectively. Symbol groups within a set are transmitted on adjacent uplink sub-frames. Five format options are defined, which map to various of the LTE TDD configurations.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Provisional Application Serial No. 62 / 564,542, entitled "NPRACH Format for NP-IoT Transmission in TDD Mode," filed September 28, 2018. technical field [0003] The present invention relates generally to wireless communication networks, and in particular to Narrowband Internet of Things (NB-IoT) Physical Random Access Channel (NPRACH) format design for Time Division Duplex (TDD) mode. Background technique [0004] Wireless communication networks capable of voice and data communication with mobile devices are ubiquitous in many parts of the world and continue to evolve in terms of technology maturity, system capacity, data rate, bandwidth, supported services, etc. A basic model of a wireless network, often referred to as "cellular," has a number of fixed network nodes (variously called base stations, radio base stations, base transceiver stations, serving nodes, NodeBs, eNobeBs, eNB...

AI Technical Summary

Problems solved by technology

This can lead to loss of coherent NPRACH across symbol groups, or force the UE to remain coherent across these discontinuities

Also, hardware introduces random phase, which can be problematic for maintaining phase coherence

[0071] Also, the requirement on the amount of delay required to detect the PRACH may have to be relaxed

In case of in-band / guard-band deployment, NB-IoT TDD configuration should follow the same configuration of LTE and there is no escape from the issue in this case

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